Currently, a semiconductor device having nonvolatile memory cells, such as an EEPROM (Electrically Erasable and Programmable ROM) or a flash memory, is generally used in diverse fields. The number of rewrites thereon, improvement of reliability such as data retention tolerance, and miniaturization of the structure are important subjects. On the other hand, a flash memory that is represented as a floating type that is in the marketplace has recently attracted attention since it is said that a resistance change nonvolatile memory device has a high reliability in addition to a simple structure, a high-speed rewrite function, and multi-value technology, and is suitable for high performance and high integration.
Since a nonvolatile memory device including a phase change RAM (PRAM) has a structure in which a resistance change layer that functions as a memory portion is arranged between two electrodes, the memory structure is simple, and easy miniaturization is possible. A nonvolatile memory device in which the resistance change layer is formed of an ionic conductor including metal is disclosed, for example, in JP-A-2008-153375. A nonvolatile memory device including a chalcogenide film is disclosed, for example, in JP-A-2006-179778.